Launch Vehicle Mission Capability Enhancement through Global Positioning System Metric Tracking
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Launch Vehicle Mission Capability Enhancement through
Global Positioning System Metric Tracking
Theodore C. Moore Michael A. Carr Henry D. Friesen
United Launch Alliance United Launch Alliance USAF AFSPC LRSW/EN
12257 S. Wadsworth Blvd1 12257 S. Wadsworth Blvd1 12782Court
MS T5009 MS H3400 Garden Grove, CA 92841
Littleton, CO 80125 Littleton, CO 80125 310-653-3725
303-977-6973 303-971-7444 henry.friesen@losangeles.af.mil
ted.c.moore@ulalaunch.com michael.a.carr@ulalaunch.com
Abstract—United Launch Alliance (ULA) and their United provide maximum mission flexibility. The GPS MT System
States Air Force (USAF) Evolved Expendable Launch will make its first flight in 2012. The certification of GPS
Vehicle (EELV) customer initiated operational flights of MT System on Atlas and Delta is expected to be completed
both the Atlas V and Delta IV launch vehicle families in in 2013.
2002. Both Launch Vehicle families have provided 100%
mission success since their respective inaugural launch and The GPS MT System will provide precise LV position,
have demonstrated launch capability from both Vandenberg velocity and timing information that can replace ground
Air Force Base (VAFB) on the Western Range and Cape radar tracking resource functionality. In its initial
Canaveral Air Force station (CCAFS) on the Eastern Test configuration, the GPS MT System will provide an
Range. However, the current EELV fleet communications, independent position/velocity S-band telemetry downlink to
tracking, & control architecture & technology, which date support the current man-in-the-loop ground-based
back to the origins of the space launch business, require commanded destruct of an anomalous flight. To enhance
support by a large and high cost ground footprint. The cost effectiveness, the GPS MT System design is
United States Air Force has embarked on an initiative implemented using existing commercial parts, common test
known as Launch Enterprise Transformation (LET) that will requirements for environments, and electrical/mechanical
significantly reduce Test Range Operations and interface requirements for both EELVs. The EELV GPS
Maintenance (O&M) cost by closing facilities and MT System design is complete and the hardware is currently
decommissioning ground assets. An important phase of the in functional and environmental qualification testing. The
LET initiative is implementation of Global Positioning system utilizes a 50 channel all in view digital receiver with
System Metric Tracking (GPS MT) on launch vehicles that high dynamic environment compensation fed by antennas
use these ranges. mounted diametrically opposed on the second stage airframe
skin. An additional benefit of the GPS MT System
GPS MT is a way to leverage the existing GPS satellite base implementation is the availability of a precise GPS time
navigation system’s capability in order to significantly base on board the vehicle to provide tighter time correlation
reduce the costs of Test Range O&M. United Launch with external instrumentation and video along with the
Alliance (ULA), in partnership with the U.S. Government, opportunity to better time synchronize vehicle dynamic and
is engaged in project plan to evolve the EELV fleet from thermal analog data. Additional system flexibility such as
dependence on ground based range assets to a Space Based the ability to power the transmitter and low noise amplifier
Range operational concept. The intial phase is development from the Global Positioning Tracking Unit (GTU) is
of the GPS MT System. ULA worked closely with the provided. The GTU also incorporates a modular
USAF to define and document the requirements for a GPS construction which allows for easy modification for future
MT System for an EELV-class launch vehicle in the Range system applications.
Commanders Council RCC324-1 document (RCC 324-01T-
EELV, Global Positioning and Inertial Measurements This paper summarizes the current development status,
Range Safety Tracking Systems’ Commonality Standard physical parameters and functional performance capabilities
Tailored for EELV). 1 of the EELV GPS MT System.
The GPS MT System satisfies those requirements by
establishing a common set of components to be
implemented on Atlas V and Delta IV. The GPS MT
System data output format is structured per the USAF Test
Range GPS Metric Tracking Interface Control Document to
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978-1-4244-7351-9/11/$26.00 ©2011 IEEE
2
IEEEAC paper #1458, Version 3, Updated Jan 9, 2011
1
TABLE OF CONTENTS ULA has teamed with our Air Force launch customer to
plan and execute the EELV Space Based Range Project in
1. INTRODUCTION………………………………………… 2
support of the Air Force Space Command’s LET vision
2. GPS MT OVERVIEW…………………………...………. 2 while enhancing the mission success and capabilities of the
EELV fleet. The first phase is development of the Global
3. DESIGN REVIEWS AND TEST………………………...…. 4 Positioning System Metric Tracking System (GPS MT).
4. CONCLUSIONS …………………………………………. 6 The GPS MT System will provide precision LV position,
velocity and timing information that can replace ground
REFERENCES……………………………………………… 7 radar tracking resources. The GPS MT System will make
BIOGRAPHY…………………………………………..…… 7 its first flight in 2012 from Cape Canaveral. The GPS MT
System will become operational in 2013.
ACKNOWLEDGEMENTS…………………………………… 7
2. GPS MT OVERVIEW
1. INTRODUCTION
The Global Positioning System Metric Tracking (GPS MT)
United Launch Alliance initiated operational flights of both System is being developed to satisfy the requirements
the Atlas V and Delta IV launch vehicle families in 2002. established by the Air Force (AF) in the Range
Both LV families have provided 100% mission success Commanders Council 324-1 (RCC 324-1) titled Global
since their respective inaugural launch and demonstrated Positioning and Inertial Measurement Range Safety
launch capability from both Vandenberg Air Force Base on Tracking Systems’ Commonality Standard as tailored for
the Western Range and Cape Canaveral on the Eastern Test EELV. This document establishes the performance and
Range. However, the current EELV fleet communications, verification requirements for the GPS MT System.
tracking, & control architecture & technology, which date
back to the origins of the space launch business, require The GPS MT System will be one of three independent range
support by a large and high cost ground footprint. The tracking sources to assist the AF Range Officer to determine
United States Air Force has embarked on an initiative the trajectory health of the vehicle. The three sources of
known as Launch Enterprise Transformation (LET) that will tracking data will include Telemetered Inertial Guidance
significantly reduce Test Range Operations and (TMIG), Launch Head Skin Track Radar and GPS MT
Maintenance (O&M) cost by closing facilities and System as depicted in Figure 1.
decommissioning ground assets.
Payload Fairing Jettison Upper Stage MECO1
Approx 914 sec
Upper Stage typically flies over the horizon
Booster/Upperstage Upperstage MES1 prior to MECO1 approx 600sec
Separation
End of Range Safety Responsibility
TMIG: Delta IV 2241.5 MHz BPSK I=1.92 Mbps Delta IV 2241.5 MHz BPSK I=192 Kbps
TMIG: Atlas V 2211 MHz QPSK/BPSK I=1024 Kbps Atlas I 2211 MHz BPSK I = 256 Kbps
Ground Station Receive, Record and Real-Time Relay TDRSS Receive, Record and Real-Time Relay
GPS 2287.5 MHz 115.2 Kbps
Ground Station Receive, Record and Real-Time Relay
Ignition
Skin Track at liftoff
VAFB / CCAFS Launch Complex
Range Safety Responsibility
Figure 1: GPS MT Signal telemetered thru End of Range Safety Responsibility
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The GPS MT System will utilize signals from the of the first engine cutoff of upper stage propulsion as
NAVSTAR GPS constellation for computing state vectors. depicted in Figure 1.
The resulting state vector data (position, velocity vectors
and time) will be transmitted to ground based S-Band The GPS MT System will be used on both the Atlas V and
telemetry receivers and processed by ULA Mission Control Delta IV series of EELV launch vehicles. The system
and cognizant Range Safety organizations at the Eastern and hardware is comprised of newly designed and tested L-band
Western flight test ranges. The GPS MT System will be antennas (Haigh Farr), Low Noise Amplifiers (Delta
operational from pre-launch activities thru Range Safety Microwave), Global Positioning System Tracking Unit
responsibility. The end of Range Safety responsibility (GTU) (Space Vector Corporation (SVC)), S-band
coincides with the vehicle going over the horizon which is transmitter (Microwave Innovations), RF Multiplexer (L-3
approximately 600 seconds into flight and prior to the end Narda) as shown in Figure 2.
RF
Combiner
GTU
GPS Satellite
Constellation
Low Noise L-band Antennas
Amplifiers
S-band
Transmitter
RF S-band Antenna
Multiplexer Range Safety
Figure 2: The GPS MT System Hardware
The heart and soul of the GPS MT System is the GTU. The Launch Vehicle –to– Range Interface Control Document
GTU utilizes signals from the NAVSTAR GPS (ICD). This ICD can be requested from the Air Force.
constellation for computing position and velocity state
vectors. At altitudes less than 230,000 ft, the position error SVC utilized a stackable module design in developing the
is required to be less than 250 ft Root Sum Squared (RSS) 3 GTU. The GTU consists of four stackable modules
sigma and the velocity error is required to be less than 3 (CPU/communication module, GPS module, Power supply
ft/sec 3 sigma. Above altitudes of 230,000 ft, the position module, Filter module) as shown in Figure 3. The module
and velocity error limits remains the same but with a approach allowed SVC to provide additional GTU interfaces
statistical confidence of 1 sigma. GPS MTS data is to accommodate both Atlas V and Delta IV unique power
telemetered to the ground receiving antenna over a single in- and ground interfaces such that the design is universal to
phase channel on the S-band frequency using Binary Phase- either vehicle as well as taking advantage of the commercial
Shift Keying (BPSK) encoding format and Pulse Code off the shelf components (COTS). The COTS receiver and
Modulation (PCM) per the IRIG 106, class 2 standard. The processor modules were easily ruggedized for the launch
detailed listing of the data that is telemetered from the vehicle environments. Interfaces were added for control
launch vehicle to the launch base appears in an Air Force: ground power (28 vdc) and vehicle power (28 vdc) control.
DC excitation voltage for the LNAs will be provided on the
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center conductor of the coax cable from the GTU via the RF current monitors are provided to the ground operation for
combiner. GTU health data as a function of voltage and monitoring via the vehicle telemetry formatter.
CPU/Comm. Module
GPS Module
Power Supply Module
Filter Module
Figure 3: The GTU Stackable module design
Prior to lift off a single skyward facing antenna, external to configurations as depicted in Figure 4 to reduce the risks to
the rocket will be routed through an RF switch internal to launches. The System Requirements Review (SRR) was
the GTU and will be used instead of the vehicle antennas conducted prior to the start of the GPS MT System
until approximately 4 minutes before liftoff. The external hardware design or vehicle modifications. The review
antenna will be used to improve constellation visibility and evaluated the allocation and verification methodology of the
will allow the GPS receiver to acquire the ephemeris data RCC 324-1 technical requirements assigned to the existing
for all satellites in view for several hours. In flight, the Atlas V and Delta IV vehicle design. A preliminary system
signals from two L-band antennas located 180° apart on the architecture, vehicle interface modifications and component
circumference of the vehicle will each routed thru the LNAs environments were defined. The information from this
for amplification and combined in the RF combiner prior to review was then flowed to the suppliers via component
being received by the GTU. specifications.
The GPS S-Band Transmitter is a dedicated 5 watt BPSK A series of component Preliminary Design Reviews (PDR)
transmitter for the GPS MT System. The GPS transmitter were conducted. The suppliers PDR provided a preliminary
will telemeter position and velocity state vectors to ground design synthesis of the hardware including schematics,
based S-Band telemetry receivers where the data will be mechanical layout, environmental analysis, part selection
processed by ULA Mission Control and by cognizant Range criteria, test philosophy, and configuration control
Safety organizations at the Eastern and Western flight test processes. Design Evaluation Tests (DET) were conducted
ranges. by the suppliers. The DET test program provided the
suppliers with an early opportunity to evaluate their design,
manufacturing processes, test equipment, and test
3. DESIGN REVIEW AND TESTS procedures against the specified requirements. The
suppliers built test units using processes that would be
implemented on the production unit and then exposed the
A series of design reviews, development and qualification units to dynamic and thermal environments at qualification
tests, and system integration tests were required to levels. Design and test issues were resolved via analysis or
implement the GPS MT System on both vehicle design modifications and the tests re-executed.
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A series of component Critical Design Reviews (CDR) were specification via the released electrical and mechanical
conducted where the suppliers demonstrated the adequacy drawings, worse case analyses, and test results from the
of their detailed design to satisfy the component DETs..
2008 2009 2010 2011 2012/2013
SRR
Component PDRs
System PDR
Component DETs
Component CDRs
System CDR
System Integration Testing
Component Qualification Tests
Component Production
Vehilce Integration
2 Atlas & 2 Delta Launches
Figure 4: GPS MT System Risk reduced thru a series of reviews and tests
The first production unit authorized for development was of margin during vibration. The defined environments
submitted to a series of Qualification tests. These tests enveloped both the Atlas and Delta vehicle environments.
demonstrated that the final design and manufacturing ULA qualification program is based on years of Atlas and
processes had a minimum of 6dB margin above the Delta lessons learned as well as MIL-STD-1540. The tests
expected flight environments with the exception of the executed as part of the qualification program are shown in
velocity specification which was demonstrated to have 3dB Table 1.
Table 1: GPS MT Qualification Tests
Test GTU Transmitter LNA Antennas RF MUX Combiner
Functional Performance x x x x x x
Handling Shock x x x x x x
Transportation Shock x x x x x x
Pyrotechnic shock x x x x x x
Vibration x x x x x x
Thermal Cycling x x x x x x
Thermal Vacuum x x x x x x
Humidity x x x x x x
Bonding x x x x x x
Electromagnetic Interference x x x x x x
Electrostatic x x x x x x
Post Disassembly Examination x x x x x x
Salt Atmosphere x
ULA conducted a System CDR once the suppliers mechanical, thermal, and dynamic analysis. RF link
completed the DET and component CDR. The System analyses were based on nominal mission trajectories.
CDR integrated the supplier design solutions and test results
into vehicle electrical and mechanical designs. ULA ULA created three labs for system integration and
demonstrated vehicle compatibility via electrical, verification as shown in Figure 5: System Integration Labs
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(SIL) verify design. There are unique SILs for an Atlas V procedures, to provide training for launch site operators and
and Delta IV configuration. The third lab is dedicated the to to assist with vehicle anomaly resolution.
the GTU receiver referred to as a GPS Simulation Lab.
The GPS Simulation Lab is used to evaluate key phase and
The Atlas V SIL and Delta IV SIL are built to vehicle code lock loop, multipath mitigation, bandwidth of filter,
schematics and utilize functional equivalent flight units. The fast reacquisition time, and tuning parameters. GPS MT
SIL testing validates the harness pin–pin configuration, telemetry data has been created and sent to the East and
vehicle grounding, power drop and current draw limits, West coast Range Safety groups for verification of range
telemetry measurements, and ground computer control. The safety hardware and software.
SIL functionality is also used to verify day of launch
Atlas V SIL Configuration Delta IV SIL Configuration
GTU
RF
Multiplexer
GTU
LNA
Spirent
Simulator
GPS Simulation
Figure 5: System Integration Labs verify design
configurations. The System also has implemented a
modular design to support future LET initiatives. The
4. CONCLUSION development and qualification tests of the GPS MT
components have been successfully completed. Production
and vehicle integration will continue thru 2011 with the first
United Launch Alliance and the Air Force have initiated the launch scheduled for early 2012. The GPS MT System will
inital phase of the Launch Enterprise Transformation with complete the certification phase in 2013.
the implementation of the GPS MT System. This system
will enhance the test range operation and maintenance
capabilities. The GPS MT System was designed with
interfaces and tested to common environments to be
interchangeable with the Atlas V and Delta IV
-6-REFERENCES Elliot (ULA), Dr. Hanchu Li (ULA), and Tim Gray (Space
Vector) for their technical review and comments.
[1] RCC 324-01T-EELV, Global Positioning and Inertial
Measurements Range Safety Tracking Systems’
Commonality Standard Tailored for EELV, April 2008.
BIOGRAPHY
Ted Moore has worked on Atlas, Titan, Galaxy Express, and
Delta product lines since 1982. He has lead design teams in
the development of tools used for ground and flight software
verification, and power distribution system for Centaur. Ted
has held various leadership positions as subcontract
manager of major suppliers, final assembly of Centaur and
Avionics System Manager. In his current position as GPS
MT Program Manager he is responsible for the
development, integration and certification of the GPS MT
System for both Atlas V and Delta IV Programs in support
of the United States Air Force Launch Enterprise
Transformation Initiative.
Mr. Carr has worked in the military avionics industry for
over 30 years. After working as a design engineer in the
area of radar intercept/signal processing and homing/inertial
system integration, he has held various leadership positions
including Avionics Manager on the High Endoatmospheric
Interceptor and Ground Based Tracking and Surveillance
Programs, Director of Communications and Tracking for the
International Space Station, Global Missile Defense
Interceptor Chief Engineer, and Delta II/IV Avionics
Director. In his current position as ULA's Director, Space
Based Range, he is responsible for evolution of the Delta &
Atlas fleet to space based communications and tracking
architecture consistent with the United States Air Force
Launch Enterprise Transformation Initiative.
Henry Friesen has spent 15 years working at McDonnell-
Douglas, Boeing and ULA. He worked on the Delta II
launch vehicle as a controls engineer and in trajectory
analysis. He has spent the last 2 years as a civilian
government employee at Los Angeles Air Force Base as the
U.S. Air Force GPS MT Program Manager. He is
responsible for the integration and certification of the GPS
MT System for both Atlas V and Delta IV programs in
support of the United States Air Force Launch Enterprise
Transformation Initiative.
ACKNOWLEDGEMENTS
The authors would like to thank our colleques Dr. Diane
Sakaguchi (Aerospace), Dr. Andrei Doran (Aerospace), Jim
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